1. Field of the Invention
The present invention relates to a disposable intra-luminal ultrasonic instrument which includes an ultrasonic catheter that has a sound wave transducer therein for directing the sound waves outwardly into tissue and for receiving echo sounds to the transducer for transmission to a visual display which displays an ultrasound picture of the tissue whereby one can determine the makeup or construction of the tissue, e.g., hard or soft. The present invention also relates to a drive shaft used in such an instrument for rotating a specialized transducer.
2. Description of the related art including information disclosed under 37 CFR Sections 1.97-1.99.
Heretofore it has been proposed in Dutch Patent Application No. 87.00632 to provide a catheter having a catheter tip with a rotatable acoustic mirror therein or a rotatable tip having an acoustic mirror therein. A flexible shaft extends from the rotatable acoustic mirror to the proximal end of the catheter where it is driven by a suitable motor situated outside the catheter. A transducer is mounted in the catheter tip opposite the rotatable acoustic mirror. Rotation of the acoustic mirror within the tip or the tip portion having the mirror thereon causes high frequency ultrasonic vibrations or sound waves emitted by the transducer to be emitted in different directions in a rotating path and the echoes of the sound waves are received by the acoustic mirror and thence by the transducer for transmission to a visual display whereby a picture can be created of the space around the catheter tip which may contain tissue or a stenotic buildup in a vessel.
A problem with the instrument having the catheter described above is that the flexible drive shaft is fairly long, i.e., at least as long as the catheter itself. With this arrangement, it is difficult to supply a torsion free rotational force through the flexible drive shaft and to drive such a long flexible drive shaft for extended periods of time without malfunctioning.
It has been suggested in Dutch Patent Application No. 87.00632 to provide a turbine driven by fluid at or near the catheter tip with the turbine having a short drive shaft coupled to the rotatable acoustic mirror.
Heretofore it has been proposed in European Patent Application Publication No. 0 139 574 to provide an endocavity probe having a motor mounted in the distal end of one embodiment of the probe. The motor rotates a mirror which reflects signals emitted by a transducer.
This probe is utilized in examining organs and the like of a body. The probe is somewhat bulky in shape and size, is intended for insertion in body cavities, is not suitable for insertion inside veins and/or arteries and does not teach a motor having stator coils mounted on a flexible circuit board and having a diameter no greater than 3 millimeters mounted in a catheter tip.
As will be described in greater detail below, the present invention in part provides an intra-luminal ultrasonic instrument having a flexible drive shaft and a transducer with improved performance characteristics avoiding resort to special turbines or motors.
A number of ultrasonic instruments for the examination and/or treatment of blood vessels have been previously proposed. Examples of these previously proposed instruments are disclosed in the following United States Patents, the disclosures of which are incorporated herein by reference:
______________________________________ Patentee U.S. Pat. No. ______________________________________ Kondo et al. 4,572,201 Yock 4,794,931 Pope et al 4,889,757 Prodian et al 4,917,097 Yock 5,000,185 Lum et al 5,003,238 Passafaro 5,010,886 Yock et al 5,029,588 Bom et al 5,176,141 Lancee et al 5,240,003 ______________________________________